Method of producing trim members



Dec. 16. 9 9 D. R. ZAREMSKI 3, 84,350

METHOD OF PRODUCING TRIM MEMBERS Filed April 28, 1965 '2 l2 v l2 .4 J. lLlI/IIIIIIIIIIIIIIIIII, I

IIIIIIIIIIII IIIIIIIIIIIII INVENTOR DONALD RZAREMSKI ATTORNEY 3,484,350 METHOD OF PRODUCING TRIM MEMBERS Donald R. Zaremski, Cheswick, Pa., assignor to Allegheny Ludlum Steel Corporation, Brackenridge, Pa., a corporation of Pennsylvania Filed Apr. 28, 1965, Ser. No. 451,429 Int. Cl. C23f 13/00; B23p 17/00 US. Cl. 204-148 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates to stainless steel trim members for automobiles, and more particularly to a method of producing stainless steel trim members for automobiles wherein the contact surfaces of the stainless steel, i.e., those surfaces which contact the automobile body are coated with a sacrificial metal, and the exposure face of the trim is free of such metal.

Stainless steels are excellent materials for trim and decorative molding members for automobiles because they 9 have outstanding resistance to corrosive elements encountered in road service; further, stainless steel has a bright, lustrous and attractive surface, and no other metal used for automotive trim provides such lasting and attractive beauty and corrosion resistance as stainless steel.

However, stainless has one limitation which detracts from its desirability as automotive trim material in that it promotes contact corrosion of the steel body of the automobile in an area around that which is contacted by the stainless steel trim member. While this contact corrosion does not detract from the appearance of the stainless steel, it does detract from the automobile appearance in that red spots and streaks appear on the automotive body in the areas around the automotive trim. Although the mechanism of such contact corrosion is not completely understood, it is believed that the contact of the stainless steel with carbon steel tends to accelerate corrosion of the carbon steel because of galvanic potential differences between stainless steel and the carbon steel. The stainless steel in its normal corrosion resistant condition is more noble in he electromotive series than the carbon steel, the difference in potential being as high as approximately one-half volt. When the stainless steel is held in contact with the carbon steel (and in this context it should be noted that contact with the painted surface of carbon steel is included) an electrolytic cell will be set up between the stainless steel and the carbon steel in the presence of an electrolyte which will accelerate the corrosion attack of the carbon steel. Water, normally encountered in driving, will serve as such an electrolyte.

It has recently been discovered that the contact surfaces of stainless steel trim members may be given a thin coating of a sacrificial metal, such as zinc or aluminum or other metal less noble than carbon steel, and when the trim members are assembled on the carbon steel body, this thin coating of metal will corrode sacrificially with respect to the mild steel of the automobile panel; hence, contact corrosion of the panel will be retarded and, in fact, eliminated, as long as there is sacrificial metal available which will be attacked preferentially to the carbon steel.

United States Patent 0 M 3,484,350 Patented Dec. 16, 1969 There have been several prior proposals for applying such thin layers of metal, but these have proved costly and impractical from a production point of view.

It is therefore a principal object of this invention to provide an improved method of providing a layer of sacrificial metal on the contact surfaces of stainless steel trim members.

Another object of this invention is the provision of an improved method of applying sacrificial metal to the contact surfaces of stainless steel automotive trim members wherein the metal is applied in strips prior to a strip being slit into multiples from which the trim members are formed.

These and other objects, together with a fuller understanding of the invention, will become apparent from the following description when taken in conjunction with the accompanying drawings in which:

FIGURES 1 and la are respectively a sectional view and a perspective view of a strip of stainless steel to which bands of sacrificial metal coating have been applied according to this invention;

FIGS. 2 and 2a are respectively a sectional view and a perspective view of two multiples slit from the strip of FIGS. 1 and la, and from which automotive trim members are formed, and

FIGS. 3 and 3a are respectively a sectional and a perspective view of roll formed automotive trim members formed from one of the multiples of FIGS. 2 and 20.

Referring now to the drawings, and particularly to FIGS. 1 and la, a portion of a strip of stainless steel is shown and designated by the reference character 10. The stainless steel strip 10 has parallel bands of sacrificial metal 12, such as aluminum or zinc, on one surface thereof. These bands of sacrificial metal 12 are located at each edge thereof and at regular intervals thereacross, the center of each hand 12 coinciding with the location of the strip at which the strip will be slit to form multiples 14 such as are shown in FIGS. 2 and 211. From each of the multiples 14, trim members 16, such as are shown in FIGS. 3 and 3a, are roll formed. Each of the trim members 16 has a contact or attachment face 18 which will be in contact with the body of an automobile when it is assembled thereon, and an exposure face which will be exposed to view when the trim members are assembled on an automotive body. As can be seen :in FIGS. 3 and 3a,

when the trim member has been formed, a band of sacrificial metal 12 will be disposed on the contact face 18 of the trim member and the exposed face 20 will be free of the sacrificial metal and will exhibit a bright, lustrous, stainless steel surface.

Referring again to FIGS. 1 and 2, it will be readily apparent that the width of the bands of sacrificial metal 12 should be equal to approximately twice the width of each of the contact faces 18 of the trim members 16. Thus, when the strip 10 is slit through the center of each of the bands 12, the resulting band at the edge of each multiple will be wide enough to cover the contact face of each trim member.

Although any metal that is less noble than carbon steel can be used as the sacrificial metal, either aluminum or zinc is preferred because of the relative availability commercially, and the relative ease with which aluminum or zinc can be applied.

With respect to the application of the sacrificial metal bands, any method which will produce such bands on the strip is satisfactory. Both aluminum and zinc can be placed on the strip by vacuum vapor deposition, and the zinc can also be applied in the form of zinc-rich paints or by electroplating. In addition to vacuum vapor deposition, aluminum bands can be applied to the strip by bonding strips of aluminum foil to the surface of the stainless steel. This bonding can be accomplished either with physical bonds, such as adhesive, or metallurgical bonds, such as are produced by rolling. These preferred methods of applying either zinc or aluminum are presented by way of illustration only, and are not intended to limit the invention in that any method which will provide strips of sacrificial metal is satisfactory to the practice of this invention.

The exact thickness of the applied strips 12 of sacrificial metal is not particularly critical other than that the strip must be thick enough to afford sacrificial protection, and for this purpose the thickness must be at least 10 inches. The maximum thickness of the strip is unimportant from a corrosion protecting standpoint; however, practical production considerations dictate that it is preferable that the strip not be any thicker than about 3 X 10' inches. Since coatings thicker than 3 l0 inches do not significantly increase the degree of protection afforded and merely add to the expense and production problems, they should be avoided.

The term stainless steel as applied in the present specification, is intended to include all the steels classified by the American Iron and Steel Institute as being standard grades of stainless steel. These include the type 400 series stainless steels that contain chromium in amounts of from about 10%, by weight, to about 30%, by weight, and generally less than 1% carbon, such as AISl types 410 and 430 and additionally the A181 type 300 series which contain, in addition to Cr and C, a nickel content of from 6 to 30% which renders the steel structure austenitic, such as AISI type 301, 302 and 304, and the 200 series steels which contain not only nickel in amounts of 1 to 10%, but also up to about 30% Mn and .60% N as additional austenitizers. Such various stainless steel analyses may contain additionally, as impurities or alloying ingredients, small amounts of P, S, Cu, Mo, Se, B, Be, Co, W, Ti, Cb, Ta, V, Zn, Al, Si, rare earths, etc. All stainless steels, however, contain chromium within the range of from about 10% to 30% and carbon up to about 1%. The Cr content in every instance is the element that primarily effects the essential property of oxidation and corrosion resistance and consequently the article of the present invention may be broadly said to be composed partly of a steel that consists essentially of carbon in an amount up to about 1%, chromium from 10 to 30% and the balance Although several embodiments of this invention have been shown and described, various adaptations and modifications may be made without departing from the scope of the appended claims.

I claim:

1. In the method of producing stainless steel automotive trim members wherein a strip of stainless steel is slit to provide at least two multiples, and wherein each of the multiples is cold formed into trim members having attachment faces adjacent their edges, and exposure faces remote from their edges, the improvement which comprises, prior to slitting providing bands of sacrificial metal less noble than the carbon steel on the strip only at each of the edges and at each location to be slit, said bands of sacrificial metal being greater in thickness than 15 10 inches and positioned to lie on the attachment faces of the finally formed trim members.

2. In the method of producing stainless steel automotive trim members wherein a strip of stainless steel is slit to provide at least two multiples, and wherein each of the multiples is cold formed into trim members having attachment faces adjacent their edges, and exposure faces remote from their edges, the improvement which comprises, prior to slitting providing bands of sacrificial metal selected from the group consisting of aluminum and zinc on the strip only at each of the edges and at each location to be slit, said bands of sacrificial metal being greater in thickness than 15 1O inches and positioned to lie on the attachment faces of the finally formed trim members.

3. The method of claim 2 wherein the bands of sacrificial metal are applied to a thickness of from 15 10- inches to 3 X 10- inches.

4. The method of claim 3 wherein the sacrificial metal is applied by vacuum vapor deposition.

5. The method of claim 3 wherein the sacrificial metal is aluminum and is applied by bonding strips of aluminum foil to the stainless steel.

6. The method of claim 3 wherein the sacrificial metal is zinc and is applied to the stainless steel by electro deposition.

7 7. The method of claim 3 wherein the sacrificial metal is zinc and is applied as zinc-rich paint.

References Cited UNITED STATES PATENTS 1,341,967 6/1920 Barrows.

1,691,491 11/1928 Nelson.

1,959,765 5/1934 Perkins 204-197 2,428,526 10/ 1947 Osterheld 204197 2,442,485 6/1948 Cook 117-107.1

2,491,225 12/1949 Stearns 204147 3,022,105 2/1962 Tjaarda 29-458 3,201,211 8/1965 Renshaw et al 29-1965 3,260,661 7/1966 Kemp et a1 204-197 3,354,063 11/1967 Shutt 204197 HOWARD S. WILLIAMS, Primary Examiner [1. TUNG, Assistant Examiner U.S. C1.X.R. 

